Combustion chambers including suddenly enlarged chamber portions



1. B. OGlLVlE 2,828,609 TION CHAMBERS INCLUDING SUDDENLY A ril 1, 1958COMBUS Filed March 26, 1951 ENLARGED CHAMBER PORTIONS v 6 Sheets-Sheet 1mveuroa z a. 06/1. we

m-ws.

IIIIIJI.

Apnl 1, 1958 I. B. OGlLVlE 2,828,609

COMBUSTION CHAMBERS INCLUDING SUDDENLY ENLARGED CHAMBER PORTIONS FiledMarch 26, 1951 6 Sheets-Sheet 2 men-roe 15. 0am we April 1, 1958 l. B.OGlLVlE 2,828,609 COMBUSTION CHAMBERS INCLUDING SUDDENLY Y ENLARGEDCHAMBER PORTIONS 6 Sheets-Sheet 3 Filed March 26, 1951 I. B. 06% weHTTEI 5' April 1, 1958 1. B. OGlLVlE COMBUSTION CHAMBERS mcwnmc SUDDENLYI ENLARGED CHAMBER PORTIONS Filed March 26, 1951 6 Sheets-Sheet 4INVENTOR I. B; 0 GILVIE April 1, 1958. 1. B. OGlLVlE 2,828,609

COMBUSTION CHAMBERS INCLUDING SUDDENLY ENLARGED CHAMBER PORTIONS FiledMarch 26, 1951 6 Sheets-Sheet 5 rwmmn I B. OGILVIE jn'ws.

April 1, 1958 l. B. OGlLVlE 2,828,609

COMBUSTION CHAMBERS INCLUDING SUDDENLY ENLARGED CHAMBER PORTIONS 6Sheets-Sheet 6 Filed March 26, 1951 METERINE RIF/cE Cam P MIN/MUM PR5:045 Sm/r or; on aim ESSURE LV OIVI'RO VA 2 C TROLLER (POROUS) mvmron I.1?. 0G! LVIE VAR/45L: QMPLACEME/V'r ATTYS.

United This invention relates to means for burning fluid fuel in aducted stream of combustion-supporting medium. While not limitedthereto, the invention is more particularly concerned with the burningof liquid fuel in a ducted airstream, as for example in a ram-jet engineor in a combustion turbine engine, either between a compressor and aturbine or in a jet pipe as a reheating system. The invention may alsobe used in the firing of boilers and such like applications.

in known combustion systems of this kind, particularly as used incombustion turbine engines, it is usual for part of t e airflow to beseparated from the main dew and used for the primary combustion ofliquid fuel supplied by a so-called atomizing spray injector into a zonethrough which the mean velocity is sufficiently below the rate of flamepropagation to avoid the flame being blown out. As combustion proceeds,it is furthermore usual to allow additional, secondary, air to mix withthe burning gases, and when combustion is substantially compiete theremainder of the airflow, amounting, say, to 65% or more of the initialsupply, is mixed with the products of combustion.

The reason for this process is that in order to keep the temperature ofthe heated airflow within the capacity of the materials available forconstruction or" the turbine it is not possible to operate with anoverall air/ fuel ratio much lower than 60 at full load, rising perhapsto 300 during idling, whereas to obtain a reasonably rapid rate ofcombustion an air/fuel ratio of the order of 15 is required.

It will be appreciated that with varying rates of initial air and fuelsupplies the air/fuel ratio in the combustion zone is bound to vary andto depart from the optimum value, thus giving rise under certainconditions to an increased length of flame. Since it is essential forthe highly heated products of combustion to be thoroughly mixed with thediluent air before passing into the turbine, and this is not readilyaccomplished with the long solid type of flame which generally resultsfrom the use of an atomizing spray injector, it is clear that a greaterlength and/ or volume of combustion chamber is necessary than would berequired if the fuel could be burnt under conditions of greaterdispersion.

The object of the present invention is to provide a combustion systemwherein the flame is more dispersed over the cross-section of the flowof combustion-supporting medium so that it has a greater ratio ofsurface area to volume. In this way improved mixing of secondary airwith the burning gases can be obtained, thereby shortening the flame,and mixing of the products of combustion with diluent medium isfacilitated, thereby further shortening the combustion chamber andsubstantially reducing the back-pressure of the system, since thislatter is produced largely at the mixing stage.

The means according to the invention for burning fluid fuel in a ductedstream of combustion-supporting medium comprise inner ducting spacedfrom the main duct and defining a path for part of the flow comprising azone of sudden enlargement wherein turbulent conditions are produced insaid stream allowing the maintenance of Patent 9 stable combustion, partof the Wall of this zone being of porous material and backed by' a fueldistribution chamber, and means following said zone for combining theburning mixture or the products of combustion in one or more stages withat least the major part of the remainder of the combustion-supportingmedium, the latter constituting diluent or secondary combustion mediumor partly diluent and partly secondary combustion medium.

Preferably the inner ducting defines a path for part of the flowcomprising at least two sudden enlargements, the first enlargementconstituting a primary zone for stable combustion, part of the wall ofthis zone being of porous material and backed by a fuel distributionchamber, and the following enlargement or enlargements constitutingsubsequent zones wherein a further stage or stages of stable combustionmay take place, with or without admission of secondarycombustion-supporting medium, and means are provided following the finalcombustion zone for combining the products of combustion with at leastthe major part of the remainder of the combustion-supporting medium.

The use of porous material for parts of combustion chambers which aresubject to intense heating has already been proposed, a cooling gas orliquid being caused to percolate through the material towards the hotside so as to carry heat away, and it has also been proposed to obtaincooling of turbine blades and reheating of the working medium betweenturbine stages by feeding liquid fuel through turbine blades havingporous surfaces. The present invention, on the contrary, is notconcerned with the cooling of highly heated parts, and although suchcooling is consequential to the means employed, it is of no functionalsignificance since, except in certain applications, the parts are notsubjected to intense heating and would not in any case attaintemperatures outside the capacities of available materials.

In the preferred arrangement the inner ducting of the system accordingto the invention defines a path of annular section to and through thecombustion zones, and diluent combustion-supporting medium passesthrough the interior and over the outside of the annular path. In thisway an annular flame of large surface in relation to its volume isobtained so that secondary medium can be readily mixed with the body ofburning gas, thereby promoting its rapid combustion, and the thinannular stream of products of combustion is easily dispersed into thediluent medium, or Vice versa.

According to a further feature of the invention the porous part of thewall of the primary combustion zone is a short cylindrical portionadjacent a shoulder constituting the first sudden enlargement.Subsequent enlargements may be formed by similar shoulders or bydeflectors or baffles which form a constriction of the combustion pathfollowed by a sudden enlargement.

A combustion chamber wherein, as already described, the inner ductingdefines a path of annular section to and through the combustion zonesmay, according to a further feature of the invention, also comprise aflame tube, including a spray injector for liquid fuel, arranged withinthe inner ducting and spaced from it by a passage for diluent medium.With such an arrangement the two fuel admission means may be usedconcurrently for the same or different fuels, or one may be used forstarting and running at low powers and be supplemented or replaced bythe other at higher powers. Instead of the two fuel admission meanssupplying fuel into separate streams of combustion-supporting mediumthey may supply into the same stream.

Several practical embodiments of the invention will now be described, byway of example, with reference to the accompanying drawings whereof:

- a a a Figure l is a sectional elevation of a combustion chamber, inaccordance with the invention, for use in a ramjet device,

Figures 2 and 3 are sectional elevations illustrating two constructionsof a dispersed combustion chamber for use in a combustion turbineengine,

Figure 4 is a view similar to Figure 2 and showing a combustion chamberin accordance with this invention which incorporates a known type offlame tube mounted within the chamber,

Figure 5 is a sectional elevation showing a part of another constructionof combustion chamber and a known form of flame tube mounted therein,

Figure 6 is a diagrammatic illustration of a gas turbine engineincorporating dispersed combustion chambers in accordance with theinvention and of means for supplying fuel thereto,

Figure 7 is a view similar to Figure 6 illustrating the application ofthe invention to an annular combustion chamber for a gas turbine engine,

Figure 8 is a diagrammatic representation of the dispersed combustionchamber shown in Figure 7 and of the connections to the various chambersthereof on the plane 8-8 of Figure 7, and

Figure 9 is a view along line 99 in Figure 4.

Referring to Figure l: the combustion system for the ram-jet device iscontained in a cylindrical length of duct 10 and comprises internalducting made up substantially of three portions, the innermost of whichis a plain cylinder 11' of diameter of about half that of the main duct10 and length about equal to the diameter of the main duct. From aposition near the upstream end 12 of portion 11, and annularly spacedoutwardly from it by a small gap 13, the second portion 14 extendsupstream in a slightly flaring manner for a distance approximately equalto the diameter of the main duct. The third portion 15 of the innerducting extends downstream from the upstream end 16 of portion 14, towhich it is attached to form a circular knife edge 17, at first in aslightly divergent form and then parallel to (as at 18) and spaced awayfrom the main duct and it finishes somewhat short of the downstream end19 of portion 11. The portions 15 and 14 are carried from the ducting 10by three angularly spaced vanes 112, and the portion 11 is carried fromthe portion 15 by vanes 90 later described. From the downstream end ofportion 14 a flat annular ring 20 extends radially outwards towardsportion 15, and in the downstream corner formed between these twomembers is arranged a ring shaped fuel distribution chamber 21 havingits inner cylindrical surface 22 made from porous sintered bronzematerial, the radial thickness of the chamber being such that itoccupies only a part of the space between portions 14 and 15 at thisposition. Fuel is supplied to the chamber 21 through a pipe 113.

Air flowing through the annular gap 13 comes to a sudden enlargement atthe downstream end of portion 14 and a turbulent eddy is set up behindthe flat annular ring 20 and over the porous surface 22. When fuel iscaused to flow through the latter and ignited a stable flame can bemaintained in this zone. About halfway between the chamber 21 and end 19of portion 11 an annular bafile 23 projects from the interior of theportion 15 partway towards portion 11 and provides (on its downstreamside) a second zone of sudden enlargement wherein a further stage ofcombustion may proceed in a stable manner.

It will thus be seen that the internal ducting defines a path for partof the airflow comprising two sudden enlargements 20 and 23 and fromwhich, according to the overall air-fuel ratio at which the device isbeing run, an annular stream of products of combustion or burning gasleaves and is combined with a central core stream of diluent orsecondary air and an outer annular stream of diluent or secondary airpassing between the main duct 10 and portion 15 of the inner ducting.

Another form of combustion chamber according to the invention is shownin Figure 2 and is suitable for use as one of a number of dispersedcombustion chambers in a combustion turbine engine as showndiagrammatically in Figure 6. Referring thereto the engine comprises acompressor 25, a gas turbine 26 to drive the compressor and a pluralityof dispersed combustion chambers 27 to which compressor 25 delivers airand in which fuel is burnt, the hot air and gases from the chamberspassing to the turbine to drive it. In Figure 6 the combustion chambers,which are shown only in diagrammatic manner, have an additional fuelsupply as required for the constructions shown in Figures 4 and S andpresently de scribed, but in other respects the arrangement isapplicable to Figures 2 and 3.

Referring to Figure 2: the combustion chamber comprises a main duct andinternal ducting similar to that described above but in which portion 15ends a short distance beyond the ring-shaped fuel distribution chamber21 while a fourth portion of ducting 30 somewhat larger than part 18overlaps the latter somewhat, and is connected to it in a manner whichprovides entry openings 31 for secondary air. The portion 30 extendsdownstream to the end of the combustion chamber, at which point a baffle32 extending inwardly from the main duct 10 restricts the passagebetween these two ducts, the baflle ending short of the ducting 3t) andleaving a small annular gap 199 between the inner periphery of thebaflle and the outer surface of the ducting 30. Somewhat downstream ofair gap 31 a flame deflector or baflie 33 extends inwardly from portion30 and in section is approximately quarter of a circle, so that thesecondary air entering through gap 31 is deflected towards the center ofthe combustion chamber. Duct 30 is provided with a ring of apertures, at34, through which diluent air passing around the outside of the internalduct system may pass and mix with the products of combustion and thediluent air flowing through the center of the system.

The innermost portion of internal ducting 35, which in the previouslydescribed construction was cylindrical and comparatively short (see part11 of Figure 1) extends in the example now being described withreference to Figure 2 upstream to a point in line with edge 17 andtapers to a somewhat smaller diameter at its downstream end, which is inline with the downstream end of portion 15 (i. e. air gap 31). In thedownstream end of portion 35 of the ducting is mounted by tabs 114 aflaring trumpet shaped deflector 36 which divides off the outer annularlayer of air and deflects it as secondary air into the combustion zonein opposition'to the stream of secondary air flowing inwardly throughthe outer gap. In this arrangement the first sudden enlargement occursat the square shoulder 20 at the downstream end of portion 14 the porousburner wall 22 being immediately adjacent this shoulder and at a largerradius. The downstream side 37 of the fuel distribution chamber 21constitutes a second enlargement while the deflecting baflie 33 produceson its downstream side a further turbulent zone of sudden enlargementwherein a further stage of combustion may proceed in a stable manner.

By way of example, the air supplied to the combustion chamber may bedivided up approximately in the following proportions: 14% through duct35, this flow being divided at the end of the duct by the trumpet shapeddeflector 36 so that 5% is secondary air going through gap 38 and 9%diluent air, 17.5% between ducts 14 and 35 into the primary combustionzone, 68.5% round the outside of duct 15, of which 9 parts pass throughthe annular gap 31 as secondary air, 52.5 parts pass through theapertures 34 as diluent air, and 7 parts pass on along the outside ofduct 30 and between it and battle 32 through annular gap as cooling air.

With this distribution of air the combustion chamber is designed tooperate with an overall air/fuel ratio of 60;l, the IBIiO in the primarycombustion zone being 10.5:1, weakening off to 19:1 at the end of thiszone where the secondary air is admitted.

The portions '15 and are carried from the ducting 10 by three angularlyspaced vanes 115, and the portion is carried from the portion 14 byvanes 116 and 90.

in the modification of the arrangement of Figure 2 shown in Figure 3 alarger proportion of air is designed to pass through the innermostportion of internal ducting (indicated by the reference and the trumpetshaped deflector 36 has an inwardly tapering frusto-conical portion 41extending about two diameters downstream from its throat. The secondaryair gaps 31 are arranged somewhat downstream of secondary air gaps 138formed between the deflector 36 and the portion 40, and a ring ofapertures 42 is provided in a short portion 43 of the duct 30 whichflares conically outwards in the direction of airflow. The outer shellor main duct 10 of this combustion chamber swells outwardly from itsupstream end and then inwardly in a streamline manner, and the internalducting is arranged to conform generally to this curvature. The portion30 is carried from the portion 15 as previously described, and theportion 15 is supported from the ducting 10 by three angularly spacedvanes 117, and the portion 40 is carried from the portion 14 by vanes120, the portion 40 carrying the deflector 36 and the portion 41.

In a combustion chamber of the general arrangement just describedportion 40 of the internal ducting, and the trumpet shaped deflector 36and its extension 41 forming an approximate continuation thereof (seeFigure 4), may be made sufficiently large in diameter to house a flametube 45 comprising a spray type fuel injector 46 (see also Figure 9).Such a flame tube may for example comprise a conical or hemisphericalupstream end 47 provided at its center with the spray injectorsurrounded by a primary air admission opening in which are mounted guidevanes 48 shaped as shown in Figure 9 to produce a swirling motion of theinflowing air. The flame tube tapers downstream from the conical end andis provided with rings of apertures 101, 102, 103 of progressivelyincreasing size for the admission of secondary air. For a length ofabout three quarters of a diameter from its downstream end the flametube has an external jacket 49 surrounding it with a small gap 50 forcooling air, the upstream end of this jacket being connected by afrustoconical portion 51 with the downstream end of the extension 41.The frusto conical portion is provided with apertures 52 for the passageof diluent air. The wall of the flame tube may also extend upstream pastthe conical end (as at 53) to a position in line with edge 17 and theupstream end of portion 40, the relative diameters of all these ducts atthis point being selected so as to meter desired proportions of theairflow into the different channels.

A combustion chamber as described with reference to Figure 4 may be usedin several different ways, for example both burners may be runconcurrently, with the result that the great dispersion of thecombustion zones makes for rapid and efflcient mixing of the products ofcombustion with the diluent air and enables the size of the combustionchamber to be kept down to a minimum. If desired, the porous burner maybe shut down during running at low power outputs. Alternatively, the twoburners may be used for different fuels, for example liquid and gaseousfuels, or the spray burner may be used for rapid starting and warmingup.

Figure 5 illustrates another construction of dispersed combustionchamber for a gas turbine engine according to this invention andincorporating a known form of flame tube. The latter, which is indicatedby the reference numeral 66, comprises a conical upstream end 61provided at its center with a spray injector 46 surrounded by a primaryair admission opening in which are mounted guide vanes 48 shaped asshown in'Figure 9 to produce aswirling motion of the inflowing air, partof-the outer wall 64 of the flame tube, downstream of a shoulder orbaffle 65, carrying a fuel distribution chamber 21 having a porous innersurface 22. Downstream of chamber 21 the wall 64 of the flame tube is.provided with openings 66 for the admission of secondary air, andbeyond this again the wall is stepped abruptly outwardly, at 67, withopenings 68 for the admission of diluent air. With such an arrangementthe spray injector 46 may be of comparatively small capacity so that itoperates as a preheating or slow running pilot system, while the mainfuel supply is through the porous wall 22.

An important application of the invention provides an annular combustionchamber for a combustion turbine as diagrammatically illustrated inFigures 7 and 8. Such a combustion chamber comprises an outer shell 70and an inner shell 74, both being substantially surfaces of revolutionand defining a duct between the compressorZS and turbine 26, andintermediate ducting 71 spaced from said shells and defining a path forpart of the airflow passing between the shells and comprising a suddenenlargement constituting a primary zone for stable combustion, aring-shaped part 72.0f the Wall of this zone being of porous materialand backed by fuel distribution chamber 21.

Each of the constructions shown in Figures 1, 2 and 3 may be made in theform of a truly annular combustion chamber in which the longitudinalsections, with respect to the direction of airflow, through the annularmain duct on either side of the axis are each similar to the singlelongitudinal section of the approximately cylindrical combustionchamber. Such arrangements provide two ring-shaped porous burnersofwhich both may be used concurrently at the higher loadings and one only,if desired, at the lower loadings, or the two burners may be used fordifferent fuels. In an annular combustion chamber of this kind theporous burners are preferably made in segments with separate fueldistribution chambers, and the fuel supply system may include means forsupplying individually metered quantities of fuel to the separate fuelchambers.

The porous material used for the burner wall must of course beunaffected by the fuel used and resistant to the maximum temperaturelikely to occur. A suitable material for this purpose is readilyavailable commercially and is composed of compressed and sinteredgranules of bronze or other metal. Such materials are graded accordingto the size of the metal granules, and the flow of fuel through them fora given supply pressure varies according to the grade. The lawconnecting the supply pressure and the fuel flow also varies accordingto the grade but does not depart greatly from direct proportionality inthe useful range. By suitable choice of material or by the use of twomaterials of different grades in combination it is possible to obtain asubstantially linear law which is sufficiently stable to allow the fuelsupply to be controlled by varying the pressure of the fuel in relationto the static pressure in the primary combustion zone. An arrangement ofthis kind is more particularly useful for ram-jet devices wheresimplicity is of more importance than accuracy of fuel control.

Such fuel supply pressures are very low in comparison with thosenecessary for the operation of the conventional spray injectors, beingonly of the order of 2 to 25 pounds per square inch.

In an alternative fuel supply system the metering of the fuel may beeffected by means of a fixed area orifice in the fuel line from a supplypump to the. fuel distribution chamber of the burner. In this system asufficiently large drop of pressure is. provided at the metering orificeto make such pressure differences as occur in the passage of the fuelthrough the porous material unimportant.

A fuel supply system of this kind suitable for use with a number ofdispersed combustion chambers each comprising aspray injector acting asa pilot burner and a porous wall "as a'main burner is illustratedschematically in Figure 6. In this figure a fuel pump 80 is driven fromthe turbine 26 by a shaft 81 and is capable, in conjunction with apressure controller 82, of maintaining a sufficiently high constantoutput pressure, say 200 pounds per square inch, to supply the pilotspray injectors 46 through a pipe 83 from a tank 86, while a branchsupply passes from the pump through a pipe 84 and a throttle controlunit 85 to distribution pipes 87 leading to the porous burners 121 ofthe individual combustion chambers through metering orifices 88. Toprevent dribbling from the porous burners when the engine is idling, aminimum pressure shut-off valve may be provided as indicated at 89, andmay operate on the well known dump valve principle to drain fuel fromthe burner. In cases in which the spray injectors are required to passvariable quantities of fuel in approximately constant ratio with theporous burners the throttle control unit may replace or followimmediately after i the pressure controller 82.

According to a further alternative method shown in Figures 7 and 8 asapplied to an annular combustion chamber 70, 74 provided with a porousburner divided into a number of separate segments by partitions 105, afuel pump 80 of the positive displacement variable output type having aworking chamber for each segment I is connected by pipes 87 to thevarious segments and is controlled as to output by a control unit 85.

Preferably the fuel is supplied to the distribution chamber in liquidform and does not evaporate until it has passed through, or nearlythrough the porous material, but it is also possible to use gaseous fuelor to vaporize liquid fuel in the distribution chamber, or in avaporizer before it reaches such chamber, so that it passes through theporous material substantially in the vapor state.

Until the burners are thoroughly warmed up there is a tendency forliquid fuel passing through to the surface of the porous material to runtowards the lower half when the combustion chamber is arrangedhorizontally, and to minimize this, short radial vanes such as 90 inFigures 1, 2 and 5 lying approximately in the direction of the airflowmay be secured to the surface of the burner, I

or alternatively, other suitable means for opposing the downward flow ofsuch fuel as may be provided. In cases in which the fuel is vaporizedbefore it reaches the combustion zone side of the porous material, or inwhich normally gaseous fuel is used, such means will not usually benecessary.

I claim:

1. In a combustion system for burning fluid fuel in a gaseous stream ofcombustion-supporting medium, ducting immersed in the said stream andcomprising first and second duct portions both extending generally inthe direction of flow of said stream and enclosing between them anannular passage open at both ends, an annular ring portion extendingradially from the downstream end of said second duct portion and awayfrom said first duct portion so as to form a sudden enlargement of saidannular passage, an annular fuel supply chamber comprising a wall ofporous material adjoining that edge of said annular ring which is themore remote from said first duct portion and extending downstream fromsaid edge, a third duct portion extending downstream from said annularfuel supply chamber, and a flame deflector spaced downstream from saidfuel supply chamber and extending part way across said passage.

2. Ducting as claimed in claim 1 wherein a fourth duct portion extendsdownstream from and forms substantially a continuation of said thirdduct portion and carries said flame deflector.

3. Ducting as claimed in claim 1 further comprising a deflector at thedownstream end of said first duct poradditional air towards said flamede- 'tional air deflector is provided with a frusto-conical portionextending downstream of the additional air deflector throat.

5. Ducting as claimed in claim 1 wherein a further duct portion forms anapproximate continuation of the first duct portion and a flame tube,comprising a'spray injector for liquid fuel, lies within said ductportions.

6. Ducting as claimed in claim 5 wherein means are provided forsupplying fuel to said injector and wall, said injector and wall beingeffective for supplying fuel into the stream of combustion-supportingmedium.

7. Ducting as claimed in claim 1 including a further duct portionforming a continuation of said first duct portion, a flame tube and aspray injector for liquid fuel lying within said duct portions and ajacket surrounding the downstream end of said flame tube, said furtherduct portion terminating in a frusto-conical portion connected to theupstream end of said jacket, said frusto-conical portion being providedwith apertures for the passage of diluent air.

8. A combustion chamber for a combustion turbine for burning fluid fuelin a combustion supporting medium, said combustion chamber comprising amain duct, and a coaxial inner ducting within said main duct com prisingan inner tubular portion, a second tubular portion surrounding saidinner tubular portion and forming with said inner portion an annularpassage for a portion of said combustion supporting medium, an annularring extending radially outwards from the downstream end of said secondportion and forming a sudden enlargement of said annular passage, anannular fuel supply chamber having a cylindrical wall of porous materialdisposed on the downstream side of said annular ring and forming acontinuation of the outer wall of said passage, a third tubular portionsurrounding said second tubular portion and fuel supply chamber andextending rearwardly therefrom, and a fourth tubular portion of largerdiameter than said third tubular portion extending downstream to therearward end of the main duct, said third and fourth portions havingoverlapping ends between which a gap is formed for the admission ofsecondary air to said fourth portion, and said fourth portion containingan inwardly projecting flame deflector.

9. A combustion chamber as claimed in claim 8,

wherein the fourth tubular portion is formed with a part of short axialextent which flares conically outwards in the direction of air flow andhas a ring of apertures for the passage of diluent air.

7 10. A combustion chamber as claimed in claim 8 including atrumpet-shaped deflector at the downstream end of the inner tubularportion for deflecting additional air towards said flame deflector.

11. A combustion chamber as claimed in claim 8 including atrumpet-shaped deflector at the downstream end of the inner tubularportion for deflecting additional air towards said flame deflector, saidtrumpet-shaped deflector being provided with a frusto-conical portionextending downstream of the deflector throat.

References Cited in the file of this patent UNITED STATES PATENTS2,405,785 Goddard Aug. 13, 1946 2,417,445 Pinkel Mar. 18, 1947 2,450,535Watson Oct. 5, 1948 2,546,432 Darling Mar. 27, 1951 2,551,112 GoddardMay 1, 1951 2,551,114 Goddard May 1, 1951 2,658,566 Wirth et al Nov. 10,19 53 FOREIGN PATENTS 266,196 Switzerland Apr. 17, 1950

